The link in my last post will let you know how to get the firmware loaded and how to install it. You will need to start DJI GO app to find out which version of firmware is on the remote controller right now. The link I sent tells you how to do that. Depending on which version you have now,will determine how to proceed. You will either be able to update the firmware on the DJI GO app or you may have to download the firmware onto a mini sd card or a thumb drive and plug that into the USB port on the remote controller.
Write down on paper which firmware version you have now, just in case you need it for reference later.